Purpose: This study aimed to find a quick and timely way to investigate the individual variation of efficacy of opioid analgesic in Chinese patients undergoing elective surgeries. Methods: 120 female patients receiving elective surgery under general anesthesia were recruited into this study. At the time of routine intravenous anesthetic induction we observe the efficacy of opioid analgesic including analgesic effect, effects on Narco-trend index, sedative effect, effects on respiratory system, and aslo effects on cardiovascular system.